1. Field of the Invention
The present invention relates to a III-nitride semiconductor device, an epitaxial substrate, and a method for fabricating the III-nitride semiconductor device.
2. Related Background Art
Non Patent Literature 1 discloses the effect of miscut in m-plane GaN substrates. The investigation was carried out using (1-100)-plane GaN substrates having miscut angles formed toward the [000-1] direction. The miscut angles were 0.45 degrees, 0.75 degrees, 5.4 degrees and 9.6 degrees. The surface morphology was improved with increase in miscut angle.
Non Patent Literature 2 discloses pyramidal hillocks on m-plane GaN. The hillocks are reduced with change in miscut angle ranging from zero degrees to 10 degrees in the direction from the a-axis to axis.
Non Patent Literature 3 discloses inclination of a crystal axis of a GaN substrate in optical properties of InGaN/GaN light emitting diodes produced on m-plane GaN substrates.
Non Patent Literature 4 describes an InGaN/GaN quantum well structure grown on semipolar (11-22)-plane GaN substrates.
Non Patent Literature 1: Hisashi Yamada et al., Jpn. J. Appl. Phys. Vol. 46, No. 46, (2007), pp. L1117-L1119
Non Patent Literature 2: A. Hirai et al., Appl. Phys. Lett. 91, 191906 (2007)
Non Patent Literature 3: Hisashi Yamada et al., J. Crystal Growth, 310, (2008), pp. 4968-4971
Non Patent Literature 4: M. Ueda et al., Appl. Phys. Lett. 89 211907 (2006)